Process for distilling coal



Dec. 5,, 1933.

H. STEVENS Filed Oct. 18 1930 PROCESS FOR DISTILLING GOAL 2 Sheets-Sheet 1 INVENTOR.

f' lw ATTORNEYS.

I Patented Dec. 5, 1933 v UNITED STATES PROCESS FOR DISTILLING COAL Harold Stevens, Cincinnati, Ohio, assignor, by mesne assignments, to Harold Stevens, trustee Application October 18, 1930. Serial No, 489,530 11 Claims (Cl. 202-13) This invention relates to distillation of coal and one of the primary objects of the invention is to increase the return obtainable from a given investment.

In this connection it has been customary to provide a bench of horizontal retorts spaced within refractory walls in such a way that hot gases can be passed over their external surfaces. Such process is handicapped by the difficulty of handling the coal into the retorts and of getting the coke out of the retorts. In addition, the retorts necessarily have a small capacity and the total capacity of a bench of such retorts is also small because the entire cross section of the 15 retorts cannot be filled, besides which there are limitations in the length to which the horizontal retorts can be practically carried. The quantity of gas which can be obtained from such a bench is a function of three things,

namely, the quantity of coal which can be carbonized as one charge in a horizontal retort of conventional dimensions, the total quantity of gas obtainable from a given amount of coal and the length of time required to completely coke a charge. It develops in practice that the relations between these factors are such that the cost of producing gas and coke with equipment of this sort has been found so high as to bring about the extended use of other types of equipment.

One such type is commonly known as the vertical retort. Such retorts with external fiues for the heating gases are generally arranged in groups as in the case of horizontal retorts.

make the long dimension greater than in the case of the horizontal since coal can be dropped into them and coke dropped out of them. In addition, the entire cross section of a vertical retort is filled with coal whereas this cannot be done conveniently with horizontally disposed 1 retorts. The vertical design, therefore, lends itself readily to the handling of large unit charges and the production of a large amount of gas and coke per single charging operation and per single retort.

But, even in the case of such externally heated, vertical retorts, the utilization of capital is still poor, since the inner portions of the charge have to be coked by means of heat passed through the coked material between them and the walls. If the process of coking be assumed to progress lineally at a uniform rate from wall toward the center, assumptions which practice shows to be Their vertical disposition makes it possible to extremely optimistic, it is obvious that the weight of material coked per unit of time will decrease continuously from the beginning toward the end of the process. The weight of evidence is that the lineal rate of progress is not constant but decreases continuously so that conditions are made still worse than just described. As a consequence of these facts, it resultsthat the coke near the walls is made very economically since the investment must be in use only a comparatively short time to produce it, whereas the coke further in, and particularly that in the core is made comparatively uneconomically since the same investment must be in use for a comparatively long time to make a comparatively small amount of coke.

Thus the return is relatively small as compared with the investment.

I propose to overcome these difliculties by my invention.

It is also an object of my invention to provide a simple and effective continuous process in which the coal is being continually charged in and the coke continuously removed, this while maintaining a good quality of gas without objectionable cracking.

I have illustrated my invention in the accompanying drawings, wherein-- Fig. 1 is a vertical section through a retort embodying my improvements and which operates to distill a charge, after which the charge is withdrawn and the new charge introduced, and

Fig.- 2 is a vertical section through a retort adapted for carrying out my improved continuous process which will be hereinafter described.

In carrying out my invention I arrange the retorts vertically as this not only facilitates introduction of a charge and removal of the coke, but also enables me to employ larger retorts which will contain a larger charge, not only because of the increased size, but also because of the fact that all of the retort space can be effectively utilized. I have shown such a vertical retort A in Fig. 1. The retort itself is surrounded with gas flues formed between the retort wall '7 and the outer wall 8. The whole is preferably enclosed in a casing 9, The charge is introduced at the top of the retort through the pipe 10 and the bottom of the retort is closed by a movable gate 11.

The charge is heated externally by introducing hot flue gas or the like into the space 12 in the hollow wall of the retort, there being a su ab e inlet or inlets and an outlet (not shown) no for securing flow through such space, it being desirable to so locate the inlet and outlet means as to secure fairly uniform distribution of heat. Such external application of heat would require a long time for completely coking the charge as the inner portions of the charge would not become heated for a long interval.

I, therefore, combine with the external heating an internal heating of the charge. For this purpose I have embedded in the charge electrical resistor means through which a current of electricity is passed. The coal adjacent the electrical resistor means becomes heated and as the coal cokes it becomes an electrical resistor, the net eifect being that the coke surrounding the initial resistor means becomes a part thereof. Thus there is a core of coke which is heated by its resistance to the passage of the current therethrough, which increases in diameter as the coking proceeds.

Thus the coke is simultaneously being heated from within the mass and from without the mass, which very materially cuts down the period of time required for coking.

In the specific embodiment shown I provide the high potential electrode 13, preferably located at the top of the retort and a low potential electrode 14 at the bottom of the retort, this electrode being preferably carried by the door 11. The high potential electrode 13 is preferably made hollow so that the initial resistor 15 may be passed therethrough. This initial resistor may comprise a metallic tube 16 filled with coke 17. It will be understood that the initial resistor is positioned in its electrodes before the charge is introduced.

The vapors and gases which are distilled off are withdrawn at any number of suitable points vertically of the retort by outlet pipes (not shown) and which pass through the wall of the retort, or at the top through the outlet 26.

When the charge has been coked, it is dumped as, for example, into the car or cars 18 and a new charge introduced and the process repeated.

Still greater returns may be obtained by operating continuously as indicated in Fig. 2. Here the retort is closed at the bottom by a number of star rollers 19 which are adapted to be rotated, or other constructions used in the art for this purpose, the closing mechanism being operated to discharge coked material at any desired rate. When starting, however, the rollers do not rotate and retain the charge.

A portion of the base structure 20 is insulated at 21 and 22 from the remainder of the construction establishing a path for current, preferably alternating.

The electrode 13' preferably extends down into the charge and in starting it is desirable to insert an initial resistor element (not shown) as before, connecting this to the member 20. A charge is now introduced, the rollers 19 not rotating. External and internal heating is ap plied as before, but the upper portion of the charge does not coke nearly as rapidly as the lower portion because of the great depth to which the electrode 13 is carried, and, if necesand this portion becomes coked relatively much more rapidly. When this portion has become adequately coked rotation of the rollers is initiated and discharge of the coke begins. At this time continuous feed of the charge is also begun and from this point onwards the charge is heated internally by the core of coke, current passing through the coke between the electrode 13' and member 20. The core of coke roughly assumes the shape of a solid cone with concave sides as more or less diagrammatically indicated at 23. If, for any reason, the circuit is broken it can be reestablished by passing a resistance rod or equivalent member down through the hollow electrode 13'.

Steam or other gaseous medium is introduced into the chamber 24 to which the coke is discharged through a pipe or pipes 25, preferably continuously. This cools the'coke to some extent and carries some of the sensible heat into the charge, thus assisting in the coking, besides which it keeps a control through regulation of the quantity of steam admitted, of the character of the gas obtained. This is because of the control of temperature thereby obtained. The steam also cools the metal parts.

As the coal initially around the high potential electrode descends it reaches the sphere of action of the internal heating and coking proceeds as indicated, and the process is continuous.

This application is acontinuation in part of my' prior application Serial No. 686,053, filed January 14th, 1924. It should also be noted that various features herein disclosed are described and claimed in one or more of the following of my copending applications: Serial No. 489,532, filed October 18th, 1930; Serial No. 489,534, filed October 18th, 1930; Serial No. 489,535, filed October 18th, 1930; Serial No. 489,536, filed October 18th, 1930.

I claimz- 1. The process of distilling coal, which consists in charging coal into a vertical retort to form a column of the coal, heating the coal to form coke from within the column outwardly by passing a current through an electrical resistor and through progressively coked portions of the column, and simultaneously heating the column externally through the retort walls.

2. The process of distilling coal, which consists in charging coal into a vertical retort to form a column of the coal, heating the coal to form coke from within the column outwardly by passing a current through an electrical resistor and through progressively coked portions of the column, and

simultaneously heating the column externally through the retort walls, the coal being charged continuously and the coked product being withdrawn continuously.

3. The process of distilling coal, which consists in arranging the coal in the formof a substantially compact column about an electrical resistor element extending longitudinally of the column, heating the coal to form coke from within the column outwardly by passing a current through said resistor'and through progressively coked portions of the column, and simultaneously heating the column externally inward.

4. The process of distilling coal, which consists in arranging the coal in the form of a substantially compact column about an electrical resistor element extending longitudinally of the column,

heating the coal to form coke from within the column outwardly by passing a current through said resistor and through progressively coked portions of the column, and simultaneously heating the column externally inwardly, said resistor being substantially of the same material as the coked product of distillation.

5. The method of distilling solid carbonizable materials containing volatilizable material, which includes arranging the carbonizable materials in an elongated vertical column, initiating heating by providing a resistance path for an electrical current through the column from end to end in the interior thereof and passing an electrical current therethrough, and completing the heating, and coking of the column by passing a current through progressively coked portions of the column, whereby the column is heated radially outwardly, adding fresh carbonizable materials to the top of the column and removing coke from the bottom of the column as the heating proceeds.

6. The method of distilling solid carbonizable material, which includes arranging the material in a column and continuously feeding the material through the column from end to end thereof in a relatively quiescent state, initiating heating of said column by providing a resistance path for an electrical current through the column from endto end in the interior thereof, and completing the heating and distillation by passing an electrical current through the progressively treated portions of the column, whereby the column is heated radially outwardly as it is fed lengthwise through the column and through the path of current flow.

7. A process for coking solid carbonizable materials, which includes arranging the material to be treated in the form of a substantially vertical elongated column having a substantially circular cross section and substantially uniform cross sectional area throughout the height of the column; initiating the coking process by positioning an electrical resistor in said column substantially centrally from end to end thereof and passing an electrical heating current through the resistor to heat the same and to heat the annularly adjacent portion of the material substantially throughout the length of the column, whereby to coke said annularly adjacent portion; and passing an electrical heating current through said coked portion from end to end of the column to heat a portion of the material which is annularly adjacent thereto throughout the length of the column, whereby the coking is carried on progressively from a central region or core extended throughout the length of the column annularly outwardly therefrom substantially to the circumference of the column.

8. The process of distilling solid carbonizable materials containing volatilizable matter, which comprises placing a charge of such materials in heat conducting relationship with a source of heat, driving off the volatilizable matter from that portion of the material lying adjacent the source by heat conducted thereto from the source, treating that portion of the charge adjacent the first treated portion by passing an electric current therethrough, to generate heat electrically in progressively treated portions, and continuing the heat generating process until substantially all portions of the charge have been heated to a treating temperature, and maintaining the treated portions substantially at the treating temperature. I 9. A process for coking solid carbonizable materials, which includes treating such materials in the form of an elongated column of substantially circular cross section having substantially uniform cross sectional area throughout the length of the column by passing an electric heating current lengthwise through the column first in a substantially central portion or region thereof whereby to coke the annularly adjacent portion of the material throughout the length of the column, and passing an electrical heating current through said coked portion from end to end of the column to heat a portion of the material which is annularly adjacent thereto throughout the length of the column, whereby the coking is carried on progressively from a central region or core extended throughout the length of the column annularly outwardly therefrom substantially to the overall confines of the column.

10. The process of distilling vapors and gases from coal and leaving coke, which comprises charging the coal into a substantially vertical retort so that the coal takes the form of a column about a substantially vertical resistor element extending therethrough, heating the charge by passing an electric current through the resistor and through the coked coal thereabout, and introducing a vapor such as steam into the retort to control the temperature of the coal therein.

11. A process for coking solid carbonizable materials, which includes treating such materials in the form of an elongated'column of substantially regular cross sectional shape and substantially uniform cross sectional area throughout the length of the column by passing an electric heating current lengthwise through the column first in a substantially central portion or region thereof whereby to coke the annularly adjacent portion of the material throughout the length of the column, and passing an electrical heating current through said coked portion from end to end of the column to heat a portion of the material which is annularly adjacent thereto throughout the length of the column, whereby the coking is carried on progressively from a central region or core extended throughout the length of the column annularly outwardly therefrom substantially to the overall confines of the column.

' HAROLD STEVENS. 

